Ependymal control of new neuron production in the adult brain

描述(申请人提供)：在整个胚胎和出生后的发育过程中，神经前体细胞/干细胞分化为分化的神经元、星形胶质细胞和少突胶质细胞。虽然这些祖细胞在胚胎发育过程中相对丰富，但它们会局限于成人大脑中的特定区域。成年小鼠室管膜下区(SVZ)是成体神经干细胞的栖息地，由多纤毛的室管膜细胞组成，呈风车状排列在脑室表面的单纤毛干细胞周围。这种小生境安排的功能意义尚不清楚，因为调节SVZ新神经元持续产生的分子机制仍不清楚。利用可诱导小鼠遗传学、蛋白质生物化学和多光子实时成像的组合，我们计划测试这一耐人寻味的假设，即室管膜细胞可能在控制成人大脑干细胞产生新神经元方面发挥关键作用。我们的初步结果显示，SVZ室管膜组织的可诱导性破坏导致成年神经发生的显著减少。我们计划通过检验以下三个假设来探讨这一观察结果：1)接头蛋白Ankyrin 3在维持成年SVZ神经发生中起关键作用；2)SVZ室管膜组织作为专门的信号枢纽保持B型星形胶质细胞的神经发生潜能；以及3)神经源性SVZ B型星形胶质细胞的分化受Foxj1+SVZ小生境前体细胞的控制。我们的研究建议探索室管膜壁龛的组织、稳定性和新神经元的产生之间的直接联系。为了使这一研究问题变得容易处理，我们开发了一种使用多光子显微镜的新的实时成像平台，一种新的原代室管膜培养方法，以及新的小鼠试剂来解决这些问题。我们理解新神经元如何在成人大脑中持续产生的方法应该具有广泛的适用性。SVZ神经干细胞及其后代被认为参与了损伤后的脑部重塑。因此，深入研究控制干细胞产生新神经元的基本细胞机制，以及室管膜邻居在这一过程中所起的关键作用，不仅可以加深我们对成体神经发生的理解，而且有助于实现干细胞作为治疗剂的最终目标。

DESCRIPTION (provided by applicant): Throughout embryonic and postnatal development, neural progenitors/stem cells give rise to differentiated neurons, astrocytes, and oligodendrocytes. While these progenitors are relatively abundant during embryogenesis, they become restricted to specialized regions in the adult brain. The adult mouse subventricular zone (SVZ) neurogenic niche, housing adult neural stem cells, consists of multiciliated ependymal cells arranged in pinwheel-like structures around monociliated stem cells at the ventricular surface. The functional significance of this niche arrangement is unclear, as molecular mechanisms regulating the continued production of new neurons from the SVZ remain unknown. Using a combination of inducible mouse genetics, protein biochemistry, and multiphoton live-imaging, we plan to test the intriguing hypothesis that ependymal cells may hold a key role in controlling new neuron production from stem cells in the adult brain. Our preliminary results showed that inducible disruption of SVZ ependymal organization resulted in dramatic reduction of adult neurogenesis. We plan to explore this observation by testing the following three hypotheses: 1) the adapter protein Ankyrin 3 plays a critical role in sustaining adult SVZ neurogenesis; 2) SVZ ependymal organization serves as specialized signaling hubs to retain neurogenic potential of type B astrocytes; and 3) differentiation of neurogenic SVZ type B astrocytes is controlled by Foxj1+ SVZ niche progenitors. Our study proposes to explore a direct connection between ependymal niche organization, stability, and production of new neurons. To make this research question tractable, we have developed a novel live-imaging platform using multiphoton microscopy, a new primary ependymal culture assay, as well as new mouse reagents to address these problems. Our approaches to understand how new neuron production is sustained in the adult brain should have wide applicability. SVZ neural stem cells and their progeny are thought to participate in brain remodeling after injuries. Therefore, tacklin the basic cellular mechanisms controlling their generation of new neurons, and the key roles played by their ependymal neighbors in this process, should further not only our understanding of adult neurogenesis, but will also help in accomplishing the eventual goal of using stem cells as therapeutic agents.